Enhancement of bovine growth hormone activity in vivo by monoclonal antibodies

Aston, R.; Holder, A. T.; Iványi, Juraj; Bomford, R.

doi:10.1016/0161-5890(87)90086-1

Cited by 63 publications

(35 citation statements)

References 23 publications

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“…This accords with the demonstration by Aston et al (1991) that this region is highly antigenic in bovine GH and that polyclonal antibodies that bind to it may enhance the biological activity of GH. MAB OA16 is able to enhance the growth-promoting properties of bovine GH in dwarf mice (Aston et al 1987) and hypophysectomised rats (Wallis et al 1987); indeed it was the most active enhancing antibody in the latter study. Variant oGH1 133-139 showed receptor-binding activity slightly reduced relative to that of oGH1 or bGH (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Radioimmunoassays were carried out by the procedure of Ray & Wallis (1982) using a polyclonal antibody prepared against bGH and a panel of five monoclonal antibodies (MABs). Monoclonal antibodies OA11, OA12, OA15 and OA16 (Aston et al 1987) were raised against oGH and MAB GH1/D4 was raised against bGH (Thorpe et al 1990). Radioreceptor assays were carried out by the method of Cadman & Wallis (1981) using microsomal receptors prepared from pregnant rabbit liver.…”

Section: Radioimmunoassays and Radioreceptor Assaysmentioning

confidence: 99%

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Production and characterisation of deletion mutants of ovine growth hormone

Sami

Wallis²,

Wallis³

1999

Journal of Molecular Endocrinology

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A number of analogues of ovine growth hormone (GH), in which regions of the hormone had been deleted, were produced by site-directed mutagenesis, and characterised by radioimmunoassays and radioreceptor assays. These analogues were based on a previously described variant (oGH1) in which an 8-residue extension replaces the N-terminal alanine of pituitary-derived ovine GH. Three analogues with deletions near the N-terminus were studied, with shorter extensions of 7 or 1-2 residues (oGH14, oGH5) or with the N-terminal sequence Ala-Phe-Pro-of pituitary-derived ovine GH replaced by Thr-Met-Ile-Thr-(oGH11). These modifications had little effect on potency in radioimmunoassays based on a polyclonal antibody and five different monoclonal antibodies (MABs), or in a radioreceptor assay, indicating that the N-terminal sequence was not included in the epitope binding to any of the monoclonal antibodies, or a major epitope binding to the polyclonal antibody, or in receptor binding site 1. A variant in which residues 133-139 were deleted retained full binding to 4 of the 5 MABs, suggesting correct folding, but markedly reduced binding to MAB OA16, suggesting that the epitope for this MAB includes some or all of these residues. This variant also failed to displace about 35% of labelled hormone from the polyclonal antibody studied, suggesting that residues 133-139 may be involved in a major epitope for this antibody. This variant showed slightly lower receptor binding activity than ovine GH. Two other deletion variantsoGH1 33-46 (equivalent to the naturally occurring 20K variant of human GH) and oGH1 [180][181][182][183][184][185][186][187][188][189][190][191] (lacking the C-terminal 12 residues) showed poor folding efficiency and solubility, and low binding to all MABs except OA15, which has a linear epitope. The results suggest that these variants were incorrectly folded, but interestingly they did retain some activity in the receptor-binding assay (respectively about 5% and 0·5% of the activity of ovine GH itself).

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Section: Discussionmentioning

confidence: 99%

Section: Radioimmunoassays and Radioreceptor Assaysmentioning

confidence: 99%

Production and characterisation of deletion mutants of ovine growth hormone

Sami

Wallis²,

Wallis³

1999

Journal of Molecular Endocrinology

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“…,1987. Their effects on hGH and bGH activities in vivo have been examined in Snell dwarf mice Aston et al 1986Aston et al , 1987 whereas the effects of MAbs on the lactogenic activity of hGH have been examined in the pigeon cropsac test (Aston et al 1986). Antibodies to the COOHterminal fragment (7kDa) of hGH were raised in Balbk mice by immunization with Freund's complete adjutant.…”

Section: Methodsmentioning

confidence: 99%

“…The MAbs used were prepared by standard techniques (Ivanyi & Davis, 1980;Aston et al 1986Aston et al ,1987 and have been characterized extensively for their specificity and isotope Aston ef al. 1986Aston ef al.…”

Section: Methodsmentioning

confidence: 99%

“…Enhancement of hGH and bovine growth hormone (bGH) activity in vivo (as measured by increased growth, cartilage metabolism, and muscle protein synthesis) has been demonstrated using hormone-MAb complexes ; Aston et al 1986Aston et al ,1987. The efficacy of the effect appears to depend on the specificity of the MAb in question; however, to date no MAb used alone has inhibited the growth-promoting activity of growth hormone (GH) in vivo.…”

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Enhancement of growth hormone activity in vivo by monoclonal antibodies: potential for autoimmunization

et al. 1988

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Enhancement of hormonal activity by monoclonal antibodies (MAbs) or polyclonal antisera has been observed in a number of systems both in vitro and in vivo. The short biological half-life of many hormones or mediators is, in itself, suggestive that prolongation of activity in the circulation would enhance activity. Indeed, during the course of insulin therapy in diabetes the development of antibodies against the hormone is often associated with an improvement in hormone activity ("depot effect") which, in some cases, appears to be beneficial to the patient. Similarly, in patients who develop antibodies whilst receiving human growth hormone (hGH) therapy, only a small proportion (5%) suffer a decreased growth rate (Ammann, 1986). Antibody-mediated enhancement of insulin activity in vitro has been achieved by virtue of the bivalent nature of antibody molecules (Schecter er al. 1!379a), indicating that the same hormone may have its activity enhanced by distinct mechanisms. A similar antibody-mediated enhancement effect was also observed for epidermal growth-factor activity in vitro (Schecter et al. 19796). In both cases the enhancement effect was attributed to facilitated cross-linking of the corresponding receptor through the hormone molecule, implying that the specificity of the antiserum employed must be such that hormone-receptor interaction is permitted.Enhancement of hGH and bovine growth hormone (bGH) activity in vivo (as measured by increased growth, cartilage metabolism, and muscle protein synthesis) has been demonstrated using hormone-MAb complexes (Holder et al. 1985; Aston et al. 1986,1987). The efficacy of the effect appears to depend on the specificity of the MAb in question; however, to date no MAb used alone has inhibited the growth-promoting activity of growth hormone (GH) in vivo. This effect is independent of MAb bivalency or antibody Fc-region-mediated targeting to the liver (Aston et al. 1986,1987).Wool-growth responses in ewes treated with ox GH were increased in animals showing antibodies to the hormone; it was proposed that decreased hormone degradation was responsible for this increased activity (Ferguson, 1954). Furthermore, improvements in GH potency in vivo have also been noted when GH is administered in a prolonged or continuous fashion, rather than in a single treatment (Clark et al. 1985).In addition to enhancement of the somatogenic activity of hGH and bGH, MAbs have also been shown to enhance the lactogenic actions of hGH and human chorionic somatomammotrophin ( h a ) . We describe here the effects of anti-hGH and bGH MAbs as well as the binding of polyclonal antisera directed towards the carboxyl-terminal region of hGH on growth rate. It is shown that there is no clear correlation between the effects of different MAbs on hormone-receptor binding and the growth-enhancement

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